Method for assembling electro-acoustical transducer diaphragm assemblies

ABSTRACT

Diaphragm assemblies are provided for use in moving coil transducers. A diaphragm has a speech coil former extending from the rear face of the diaphragm. The complete surfaces of the diaphragm and the speech coil former are coated with a metallic layer, and sections of the layer are removed from the former to provide the speech coil.

United States Patent [72] Inventor Michael Lawrence Gaylord Hariow, Essex, England [21 1 Appl. No. 14,723

(22] Filed Feb. 24, 1970 [45] Patented Jane 22, 1971 [73] Assignee International Standard Electric Corporation [32] Priority Aug. 3, 1965 [33] Great Britain Continuation of appieation Ser. No. v

(54] HOD FOR ASSEMBLING ELECTRO- ACOUSTICAL TRANSDUCER DIAPHRAGM ASSEMBLIES 4 Claims, 7 Drawing Figs.

52 us. (21...; 179/11s.svc, 181/32 R, 29/594 [51] lnt.Cl H04r 9/04 [56] References Cited UNITED STATES PATENTS 1,971,452 8/1934 l-lerrrnann 179/1155 3,111,187 11/1963 Barlow 181/32 3,247,927 4/1966 Cragg 181/32 Primary Examiner-Ralph D. Blakeslee Attorneys-C. Cornell Remsen, Jr., Rayson P. Morris, Percy P. Lantzy, .1. Warren Whitesel, Phillip A. Weiss and Delbert P. Warner ABSTRACT: Diaphragm assemblies are provided for use in moving coil transducers. A diaphragm has a speech coil former extending from the rear face of the diaphragm. The complete surfaces of the diaphragm and the speech coil former are coated with a metallic layer, and sections of the layer are removed from the former to provide the speech coil.

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This application is a continuation of application No. 568047, filed July 27, I966, now abandoned.

The invention'relates to diaphragm assemblies for use in moving coil transducers.

According to the invention there is provided a diaphragm assembly for use in moving coil transducers, comprising a diaphragm with a speech coil former extending from the rear face, the complete surface of said speech coil former being coated by appropriate means with a metallic layer, sections of said metallic layer being removed by appropriate means to provide a speech coil in the fonn of spiral metallic strips.

The foregoing and other features according to this invention will be understood from the following description with reference to the accompanying drawings, in which:

FIG. 1 shows a molded circular diaphragm with integral speech coil.

FIG. 2(A) shows a plan view and FIG. 2(B) shows a sectioned front view taken along line X-X in FIG. 2(A) of a typical unit which includes the diaphragm with integral speech coil shown in FIG. 1.

FIG. 3 shows alternative methods of construction for the diaphragm with integral speech coil shown in FIG. 1.

Referring to FIG.- 1, a molded circular diaphragm with integral speech coil is shown; the moulded circular diaphragm with integral speech coil former 1, shown in FIG. 1(A), is made from 2 to 3 mils thick insulating material, for example plastic. A 1 mil thick metallized layer 3, for example aluminum is applied to the rear face 2 of the molding l by appropriate means, for example hot spraying, plating or evaporation, to give the structure shown in FIG. 1(B). The final structure shown in FIG. 1(C) is obtained by cutting sections of the metallized layer 3 by, for example precision micro engraving techniques, air abrasion, photo etching, electron beam cutting etc. to expose the underlying molding 1 thereby providing the spiral metallic conducting strips 4 and 5 respectively on the outer and inner surfaces of the speech coil support section 6 of the molding 1. Thin evaporated metallized layers may be thickened up over the coil area by selectively plating before or after cutting the spiral metallic conducting strips 4 and 5. The spiral metallic conducting strips 4 and 5 which may be 2 to 3 mils wide with one-half mil spacings between each turn, are connected in series-aiding" by the metallized coating 7 on the bottom rim of the speech coil support 6 giving a speech coil with 50 to I50 turns at an impedance of 200 to 600 ohms. Alternatively, one-half mil wide spiral conducting strips with 0.7 micron spacing may be obtained using the electron beam method for cutting the metallized layer 3.

Referring to FIG. 2, a plan view (FIG. 2(A)] and a sectioned front view [FIG. 2(8)] of a typical unit which includes the diaphragm with integral speech coil shown in FIG. 1 is shown and comprises an outer metal case 8, diaphragm with integral speech coil 1, front cover '15, acoustic resistance element l6, magnet 17, outer pole piece 20, spacer 21 and inner pole piece 22. Contact to one end of the speech coil 4 and 5 is made by the outer metallized layer 3 on the molding 1 to the outer metal case 8 by way of the contact foil 23, the outer metal case 8 has a contact lead 18 connected to it by, for example welding using pressure techniques or conducting cement. The fine inner contact lead 9 is connected to the other end of the speech coil 4 and 5 by the inner metallized layer 3 on the moulding l, the contact lead 9 being connected to the inner metallized layer 3 by the techniques previously described. The center contact output lead 19 is connected to the contact lead 9 by way of the magnet 17 and inner pole piece 22, the contact leads 9 and 19 being connected respectively to the inner pole piece 22 and the magnet 17 by anyone of the techniques previously described.

Referring TO FIG. 3a and FIG. 3b, alternative methods for producing the molded circular diaphragm and speech coil support 1 shown in FIG. 1(A) are shown. FIG. 3a shows a separately molded dome and former It) connected by appropriate means, for example heat welding or cementing to the molded surround 11, whilst FIG. 3b shows a further arrangement which consists of a separately molded dome 12 cemented by appropriate means to a molded surround and speech coil support 13.

The moulded circular diaphragm with integral speech coil is suitable for direct operation of microphones and earphones from telephone lines and/or transistorized amplifiers and the construction of this unit ensures greatly simplified or automated manufacturing techniques and offers good reliability.

It is to be understood that the foregoing description of specific examples of this invention is made by way of example only and is not to be considered as a limitation on its scope.

I claim:

I. A method for fabricating a diaphragm assembly for use in moving coil transducers comprising the steps of: molding a diaphragm and speech coil former,

forming said diaphragm assembly from said molded diaphragm and speech coil former in a manner such that said speech coil former extends from the rear of said diaphragm,

coating said speech coil former with a metallic layer, and

removing sections of said metallic layer to provide a speech coil in the form of spiral strips.

2. The method of claim 1 wherein said coating is accomplished by plating and wherein said removing is accomplished by photo etching.

3. The method of claim 1 wherein contact leads are connected to the speech coil using conducting cement.

4. The method of claim 1 wherein said diaphragm and said speech coil former are molded separately and including the step of connecting the separately molded sections. 

1. A method for fabricating a diaphragm assembly for use in moving coil transducers comprising the steps of: molding a diaphragm and speech coil former, forming said diaphragm assembly from said molded diaphragm and speech coil former in a manner such that said speech coil former extends from the rear of said diaphragm, coating said speech coil former with a metallic layer, and removing sections of said metallic layer to provide a speech coil in the form of spiral strips.
 2. The method of claim 1 wherein said coating is accomplished by plating and wherein said removing is accomplished by photo etching.
 3. The method of claim 1 wherein contact leads are connected to the speech coil using conducting cement.
 4. The method of claim 1 wherein said diaphragm and said speech coil former are molded separately and including the step of connecting the separately molded sections. 